A common method of reducing errors in force transducer systems is to use a push-pull arrangement in which two well matched force sensing elements are configured such that they are subjected to forces in opposite directions. The purpose of this arrangement is to cancel common mode errors, such as even order nonlinearities, bias temperature sensitivity, clock sensitivity, bias aging drift, and pressure sensitivity.
Problems arise when a push-pull arrangement is implemented in a physical device. For example, to utilize push-pull force sensing elements in a pendulous accelerometer, two force sensing elements are both connected to a common proof mass. The force sensing elements typically extend either perpendicular to or parallel to the pendulous axis of the accelerometer. However in such a configuration, any thermal expansion mismatch between the support/proof mass assembly and the force sensing elements creates thermal strains that in turn create large common mode error signals that can only be partially suppressed by signal processing techniques. As a result, the force sensing elements should be physically matched in all sensitivities, in order to provide a high level of common mode rejection. This close matching is often difficult to achieve.